Copper base alloy containing titanium and antimony

ABSTRACT

Disclosed are alloy compositions consisting essentially of copper and small amounts of titanium and antimony within stated ranges. These compositions have high electrical conductivity, high strength and high ductility as compared with copper alloys containing either titanium or antimony. The disclosed ranges of alloy compositions provide a class of copper-base alloys having a unique flexibility with regard to electrical, mechanical and physical properties. By varying the relative and total amounts of titanium and antimony, copper-base alloys having predictable and differing properties may be obtained. Method for the heat treatment and fabrication of the alloys are also disclosed.

United States Patent 91 Nesslage et al.

[ COPPER BASE ALLOY CONTAINING TITANIUM AND ANTIMONY [75] Inventors: Donald J. Nesslage, Old Bridge; Lin

S. Yu, Franklin Park, both of NJ.

[73] Assignee: Phelps Dodge Industries, Inc., New

York, N.Y.

221 Filed: Sept. 25, 1972 21 Appl. No.: 292,186

[52] US. Cl. 75/164, 75/153 [51] Int. Cl. C22c 9/00 [58] Field of Search 75/153, 154, 156,

[56] References Cited UNITED STATES PATENTS Nov. 20, 1973 Primary Examiner-Charles N. Lovell Attorney-William F. Kilgannon ABSTRACT Disclosed are alloy compositions consisting essentially of copper and small amounts of titanium and antimony within stated ranges. These compositions have high electrical conductivity, high strength and high ductility as compared with copper alloys containing either titanium or antimony. The disclosed ranges of alloy compositions provide a class of copper-base alloys having a unique flexibility with regard to electrical, mechanical and physical properties. By varying the relative and-total amounts of titanium and antimony, copper-base alloys having predictable and differing properties may be obtained. Method for the heat treatment and fabrication of the alloys are also disclosed.

5 Claims, 2 Drawing Figures Patented Nov. 20,1973 I O O O O 8 6 4 2 Figu ret .20 .40 .80 Antimony Weight Fraction Of Totot Alloying Concentration Figure2 L Weight/ Toto| Alloying Concentration O O O O 8 7 6 5 COPPER BASE ALLOY CONTAINING TITANIUM AND ANTIMONY The invention relates to copper-base alloys that are particularly useful as conductors in applications requiring greater tensile strength or greater ductility at a given tensile strength than possessed by pure copper.

Copper-base alloys, that is, alloys wherein copper is the predominant component, containing both titanium and antimony have not been found in the literature.

' Copper-titanium alloys and alloys having copper and titanium with lead, tin or zinc are known. See U.S. Pats. Nos. 2,616,800 and 935,863, respectively.

This invention relates to copper-base alloy compositions, and more particularly to copper-base alloy compositions containing small amounts of titanium and antimony within stated ranges.

It is an object of this invention to provide a class of copper-base alloy compositions wherein the electrical, mechanical and physical properties of copper may be predictably modified by altering the relative and total concentration of titanium and antimony, the alloying elements. 7

It is a further object of this invention to provide copper-base alloys possessing high electrical conductivity, high strength and high ductility, as compared with copper-base alloys containing either titanium or antimony.

It is a further object of this invention to provide methods for the heat treatment and fabrication of the copper-base alloys disclosed.

The class of copper-base alloys of the present invention consists essentially of titanium, antimony and a copper base, the titanium being present in an amount from about 0.08 to about 0.7 weight percent and the antimony from about 0.05 to about 1 weight percent.

Pure copper (Copper Development Association Copper No. 102) in spring temper characteristically possesses an lACS (International Annealed Copper Standard) conductivity of 101 percent and a UTS (ultimate tensile strength) of 55,000 psi with a ductility of four percent elongation in two inches, while certain compositions of the class of copper alloys of this invention possess, when properly processed, electrical conductivities in excess of 85 percent lACS and tensile strengths of over 60,000 psi with ductilities greater than 12 percent elongation in two inches. Other compositions possess electrical conductivities in excess of 75 percent lACS and tensile strengths of over 80,000 psi with ductilities greater than 8 percent elongation in 2 inches.

The alteration in the electrical, mechanical, and physical properties of the copper-base alloys is attained by varying the relative and total amounts of the alloying elements, titanium and antimony. The effects of these variances are shown in Table l. (The tables herein report only the titanium and antimony content. It should be understood that the balance of the alloy composition is essentially copper. Throughout the specification RT reduction in thickness, Y5 yield strength, and R, Rockwell 8" method.)

TABLE I Properties of Cu-Ti-Sb Alloys Cold Rolled 75% RT, Aged at 800 F for 2 Hrs; Cold Rolled 60% RT, Re-aged at 700 F for l Hr.

As the data of Table I demonstrate, the electrical conductivity of the copper-base alloys decreases with increasing titanium content, and the ultimate tensile strength increases. The data also illustrate that for any given titanium content, a greater value of electrical conductivity is achieved by maintaining the amount of antimony at 0.3 to 0.8 weight fraction of the total alloying concentration, total alloying concentration being defined as the sum of the antimony and titanium content of the alloy. For example, copper-base alloys containing 0.10 weight percent titanium and 0.l7 weight percent antimony or 0.14 weight percent titanium and 0.19 weight percent antimony, yield, respectively, electrical conductivities of 87 percent and percent IACS, while copper-base alloys containing 0.1 1 weight percent titanium and 0.33 weight percent antimony, or 0.13 weight percent titanium and 0.05 weight percent antimony yield, respectively, electrical conduc'tivities of 74 percent and 73 percent lACS. The preferred antimony range is from about 0.56.to about 0.61 weight fraction of the total alloying concentration.

The foregoing are more clearly illustrated in the figures, wherein:

FIG. 1 shows electrical conductivity as a function of fixed weight percents of titanium and the relative antimony content of the total allowing concentration; and

FIG. 2 shows ultimate tensile strength as a function of the total alloying concentration.

In the drawings, FIG. 1 is a graph which shows the relationship of the electrical conductivity of the copperbase alloy to its titanium and relative antimony content when the alloy is processed in a preferable manner. Each curve represents the effect of antimony concentration on the conductivity of a copper-base alloy with a given titanium content. It may be seen that although the titanium content produces a pronounced effect on the electrical conductivities of this alloy, the relative antimony content also exerts an important influence. In particular, increased electrical conductivity is observed with an antimony content between 0.3 and 0.8 weight fraction of the total alloying concentration, with the preferred range of antimony content being from about 0.56 to about 0.61 weight fraction.

FIG. 2 is a graph which represents the effect of total alloy content on the ultimate tensile strength of the copper-base alloy disclosed, when the alloy is processed in a preferable manner. it may be seen that additions of titanium and antimony, in the preferred relative proportions disclosed above, markedly increase the ultimate tensile strength of the copper-base alloy up to a total alloy content of about one weight percent. Beyond this, the gain in ultimate tensile strength with increased alloy additions is somewhat less significant.

The effects of alloying titanium and antimony with copper as disclosed are such that alloy composition ranges may be chosen from within the overall composition range disclosed in order to provide alloys with properties optimally balanced as desired. As is evident from Table l, relatively high electrical conductivity, and a high tensile strength with improved ductility, are available where the titanium content is from about 0.1 weight percent to about 0.2 weight percent, if greater emphasis on the electrical conductivity is desired, and from about 0.3 weight percent to about 0.4 weight percent if greater emphasis on tensile strength is chosen.

Throughout the specification, the values given for electrical, mechanical or physical parameters are those found for the indicated composition after the alloy has been processed according to one of the procedures set forth hereafter.

The following examples will serve to illustrate the nature of some of the available optimizations disclosed.

EXAMPLE I TABLE II Properties of Copper-Base Alloy Containing 0.10 to 0.23 wt.

Titanium and 0.10 to 0.36 wt. Antimony* Property Mean Value 99% Confidence Limits Electrical Conductivity 83.5% IACS 81.3% to 85.6% lACS Ultimate Tensile Strength 67,300 psi 63,000 to 7l,500 psi Yield Strength at 0.5% Extension 62,700 psi 57,500 to 67,800 psi Elongation in 2 Inches ll.7% l0.l% to 13.2%

' Alloys processed by cold-rolling 75% reduction in thickness from hot-worked condition, heat-treating at 800 F for 2 hours, cold-rolling another 60% reduction in thickness, and heat-treating at 700 F for l hour.

EXAMPLE ll An alloy with excellent tensile strength may be obtained with some sacrifice of electrical conductivity in the range of from about 0.3 to about 0.4 weight percent titanium, with the antimony content from about 0.56 to about 0.61 weight fraction of the total alloying c0ncentration, as illustrated in Table III. The properties are derived by statistical analysis of the relevant data of Table I.

TABLE III Properties of Copper-Base Alloy Containing 0.30 to 0.43 wt. percent Titanium and Antimony from 0.56 to 0.61 Weight Fraction of TOTAL ALLOYING CONCENTRATION* Property Mean Value 99% Confidence Limits Electrical 75.2% lACS 74.0% to 76.4% lACS Conductivity Ultimate Tensile Strength 80,200 psi 78,200 to 82,100 psi Yield Strength at 0.5% Extension 78,500 psi 75,900 to 81,000 psi Elongation in 2 inches ll% 7% to 15% Alloys processed by cold-rolling reduction in thickness from hot-worked condition, heat-treating at 800 F for 2 hours, cold-rolling another 60% reduction in thickness, and heat-treating at 700 F for l hour.

Small amounts of intentionally or unintentionally added impurities, such as those contained in the master alloys or residual deoxidizers, do not significantly change the mechanical and physical properties of the alloys.

In manufacturing the alloys, it is preferred to use oxygen-free copper or electrolytic copper, although other high purity coppers may also be utilized. The alloying ingredient may be in any form suitable for alloying purposes, such as metal sponges, master alloys, and so on. Conventional melting, alloying and casting practices may be utilized. A particularly good practice is to melt the copper in an induction furnace under a charcoal cover of protective atmosphere, or under vacuum.

Deoxidization may be made with a chemical deoxidizer, if so desired, without detrimental effects on the properties of the alloys, as illustrated in the following Example.

EXAMPLE "I In a comparison test, an alloy containing 0.10 weight percent titanium and 0.15 weight percent antimony resulted in an electrical conductivity of 86% IACS, a tensile strength of 62,000 psi, and a ductility of 12.5% elongation in 2 inches, while another alloy of the same composition but deoxidized with lithium during melting resulted in a conductivity of IACS, a tensile strength of 62,500 psi, and 12 percent elongation in 2 inches.

It is a preferred to cast the alloys into billets or wire bars of conventional sizes and subject them to hotworking, as by hot-rolling, extrusion, and so forth. Hotworking can be carried out at any elevated temperature below the alloys melting point, with a range of from about l,500 to l,750 F being preferred. The alloys should then be cooled rapidly, cold-worked as by coldrolling or drawing, and heat-treated. Cold-working and the subsequent heat treatment, henceforth referred to as aging treatment, are necessary to develop the optimum properties.

An alternative is to give the alloys a solution heat treatment at temperatures above l,500 F after casting, hot-working or cold-working, and then subject them to cold deformation or aging heat treatment, or both. Aging without prior cold work may result in inferior properties, however.

The aging temperature and the time depend on the degree of cold deformation. Generally, smaller amounts of cold work require a higher aging temperature or a longer aging time or both. The ultimate properties will not be the same with different cold workaging schedules. By way of illustration, the properties of an alloy resulting from different processing schedules are given in thefollowing example.

EXAMPLE IV Table IV Alloy Composition; 0.10 wt.% Ti & 0.15 wt.% Sb

Reduction Aging Tempera- Electrical Hardby ture and Conductivity ness Cold-Rolling Time IACS R 90 800 F 1.25 hrs. 86 62 90 750 F, 4 hrs. 85 72 60 800 F, 4 hrs. 85.5 69 6O 750 F, 5 hrs. 82.5 74

It is seen that the electrical conductivity and hardness values vary somewhat.

The dependence of properties on cold-working and aging treatments offers an easily accessible means of controlling the properties of the alloys. Example IV also reveals the excellent resistance to annealing characteristics of the copper-base alloys of the present invention.

In general, an initial cold reduction of less than about 85% necessitates further cold-working and aging treatments to yield alloys having optimum properties. Also, for the same total amount of cold reduction two or more cold work-aging cycles generally result in higher electrical conductivity and tensile strength than a single cycle treatment. The effect of cold work and aging cycle treatments on the properties of the alloys are more fully understandable from the following example.

EXAMPLE V TABLE V [Compositlonz 0.33 Wt. percent Ti and 0.42 wt. percent Sb] Elec- Tensile properties trical conduc- Percent tivity, Hard- YS elongapercent ness, UTS (0.1% tion in Treatment IACS R13 (p.s.i.) ofiset) 2 inches Cold-roll RT, age at 800 F. for 3 hrs 74 84 74, 200 67, 600 12 Cold-roll RT, age at 750 F. f0r4 hrs 71 91 80,700 75,400 11'. 5 Cold-r011 75% RT, age at 800 F. for 2 hrs; cold-roll 60% RT, re-age at 700 F. for 1 hr. (90 total reduction by cold-rolling) 75 92 87,000 79,200 7 In Examples IV and V the different amounts of cold work and the different aging treatments are adopted solely for the purpose of illustration.

The alloys disclosed may be used where some sacrifice in electrical conductivity may be made in exchange for tensile strength or ductility, or both, greater than that of pure copper. Some examples would be their use in switch components, electrical contacts, electrical current-carrying springs, lead frames for semiconductive devices, and high-strength hookup wires and cable.

We claim:

1. An alloy consisting essentially of from about 0.08 to about 0.7 weight percent titanium, from about 0.05 to about 1 weight percent antimony and balance copper.

2. The copper-base alloy of claim 1 wherein the antimony content is from about 0.3 to about 0.8 weight fraction of the combined weights of antimony and titanium.

3. The copper-base alloy of claim 2 wherein the antimony content is from about 0.56 to about 0.61 weight fraction of the combined weights of antimony and titanium.

4. For relatively high electrical conductivity with good tensile strength and good ductility, the copperbase alloy of claim 3 wherein the titanium content is from about 0.1 to about 0.2 weight percent.

5. For relatively high tensile strength with good electrical conductivity and good ductility, the copper-base alloy of claim 3 wherein the titanium content is from about 0.3 to about 0.4 weight percent.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,773 ,505 Dated November 1973 Inventor) DONALD J. NE'SSLAGE and LIN s. YU

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

F" I I o o Col. 4, line 55, "85%" should be -86%-.

Col. 6, line 8, -"7,600" should be -67,700-'-.

Signed and sealed this 2nd day of April l97L3..

(SEAL) Attest:

'c MARSHALL DANN Commissioner of Patents EDWARD I' LFLETCHERJR. Attesting Officer 

2. The copper-base alloy of claim 1 wherein the antimony content is from about 0.3 to about 0.8 weight fraction of the combined weights of antimony and titanium.
 3. The copper-base alloy of claim 2 wherein the antimony content is from about 0.56 to about 0.61 weight fraction of the combined weights of antimony and titanium.
 4. For relatively high electrical conductivity with good tensile strength and good ductility, the copper-base alloy of claim 3 wherein the titanium content is from about 0.1 to about 0.2 weight percent.
 5. For relatively high tensile strength with good electrical conductivity and good ductility, the copper-base alloy of claim 3 wherein the titanium content is from about 0.3 to about 0.4 weight percent. 